1. Field of the Invention
The invention relates generally to equipment for heating food products, and more particularly to an improved grill of the type having rotary heating elements.
2. Description of Related Art
Grills having cylindrical rotary heating elements are utilized in convenience store locations and other food service environments to heat products such as hot dogs, sausages, etc. The food products are rotated about their longitudinal axes on the rotary heating elements. The rotary heating elements, or rollers, are typically arranged parallel to one another and closely spaced in a horizontal array, and are driven to rotate at the same angular velocity. The rollers have internal heating elements thermally coupled to their external food-engaging surfaces. The rollers may have thermally conductive non-stick coatings of PTFE or other materials. Each food item is supported by a pair of adjacent rollers. One example of the prior art in this field is U.S. Pat. No. 2,185,979.
In order for products to roll and heat properly on prior art grills of this type, the food products must be substantially cylindrical in shape. Certain items, such as hot dog buns and next generation products currently under development (including dough enrobed, or wrapped products) can experience difficulty rolling on the grill. This may be due to the overall shape of the product, inconsistencies in the shape of the product, or imperfections (i.e., seams, blisters, etc.) in the outer surface of the food product. In addition, products that are cylindrical but of large or small diameter may not roll properly due to the angle of contact of product to roller, or the ratio of product size to contact surface with the roller. Products that do not roll properly will not heat uniformly, and will burn at higher grill temperatures. It is a general object of the invention to provide a commercially viable grill of the type having rotary heating elements wherein the grill is capable of evenly heating problematic products such as those mentioned above, as well as products that have commonly been heated on grills of this type in the past, without burning or otherwise damaging the food products.
The invention provides an improved grill of the type having rotary heating elements, and a method of modifying a grill of this type to enable substantially uniform heating of food items that heretofore could not reliably be heated uniformly on grills of this type.
The grill preferably comprises a plurality of rollers disposed closely spaced in a generally horizontal array substantially parallel to one another and rotating generally in the same rotational direction. Each roller has an external heating surface and at least one internal heating element thermally coupled to the external heating surface to transfer heat to a food product in contact with the external heating surface.
In accordance with the invention, the grill preferably further includes engagement means for improving engagement between at least one of the rollers and the food product in contact therewith by providing a locally varied effective radius of the external heating surface along a segment of the roller. The engagement means preferably is in direct contact with the external heating surface to provide heat transfer to the food product through the engagement means. In one embodiment, the engagement means comprises a grid of helically disposed wire. In a second embodiment, the engagement means provides a grid of longitudinally and circumferentially disposed wire. In additional embodiments, the invention comprises circumferential bands of various configurations.
The engagement means may comprise removable attachments which can be retrofitted on rollers and which may be readily removed therefrom to facilitate cleaning. The removable attachments preferably are capable of installation without any disassembly of the grill. The removable attachments may comprise resilient, generally C-shaped bands that snap on to the rollers. In other embodiments, the engagement means may be integral with the external surface of the roller in a one-piece unitary structure. The engagement means may include teeth, ribs, or other projections, or a plurality of slots, indentations or the like.
One of the problems encountered in configuring the engagement means is that, with certain configurations and angular velocities, the engagement means on one roller may cause the food item to be displaced from its desired position. The engagement means preferably is configured to avoid this problem. Also, the engagement means preferably does not contact adjacent rollers or engagement means thereon.
The improved grill may be employed for uniform heating of food products such as hot dogs, sausages, buns, ears of corn, carrots and other items of generally cylindrical configuration.